code: def gen_BrownianMotion():
      X = np.arange(0, 5, 0.01)
      y = np.random.standard_normal((500,))
      Y = np.cumsum(y) * np.sqrt(0.01)
      B = scipy.interpolate.interp1d(X, Y, bounds_error=0)
      return B
  
file_path: nipy/nipy/modalities/fmri/tests/test_aliases.py
imports: import numpy
  import pytest
  import scipy.interpolate
  import sympy
  from numpy.testing import assert_almost_equal
  from sympy.utilities.lambdify import implemented_function, lambdify
label_desc: Use image node_id 3 for calling a global function with example usage: gen_BrownianMotion() and returns: B